US3491987A

US3491987A - Valve tray

Info

Publication number: US3491987A
Application number: US680532A
Authority: US
Inventors: John S Eckert
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1967-11-03
Filing date: 1967-11-03
Publication date: 1970-01-27
Anticipated expiration: 1987-01-27
Also published as: GB1225410A; FR1573341A; DE1775492A1

Description

Jan. 27, 1970' J. 5. ECKERT 3,491,981"

VALVE TRAY Filed Nov. 5, 1967 2 Sheets-Sheet 2 INVENTOR. JOHN S. ECKERT ATTORNEYS United States Patent 3,491,987 VALVE TRAY John S. Eckert, Silver Lake, Ohio, assignor, by mesne assignments, to Norton Company, a corporation of Massachusetts Filed Nov. 3, 1967, Ser. No. 680,532 Int. Cl. B0111 3/ 72 US. Cl. 261-113 2 Claims ABSTRACT OF THE DISCLOSURE A valve tray for gas and liquid contact apparatus having apertures and a valve associated with each aperture; and a rigid structural interconnect between at least two adjacent valves to inhibit rotation of the valves and minimize the weeping phenomenon.

This invention relates to the art of gas and liquid contact apparatus, and more particularly to an improved valve tray.

The present invention is particularly applicable as a modification for sieve trays, and will be described with particular reference thereto; however, it will be appreciated that the invention has broader applicability and may be used in conjunction with imperforate trays, as well as other mass transfer plates.

Due to their simplicity of design and the absence of moving parts, sieve trays have been used to advantage in gas and liquid contact apparatus. However, the very features which make sieve trays attractive for use in certain applications, impose rather severe limitations on the utility of sieve trays in other mass transfer processes.

It is characteristic of a sieve tray that it has a poor turn-down ratio, i.e., the ratio of maximum to minimum throughput. Since the apertures in a sieve tray are of fixed dimension, the tray operates at peak performance only over a fairly narrow range of gas velocities. Any attempt to increase gas throughput beyond an optimum value, will merely increase the pressure drop through the plate decreasing the efliciency, without substantially increasing the capacity of the tray.

To some extent the performance limitations of the sieve tray have been offset by providing the tray with floating valves. At low operating gas velocities, these valves remain seated around apertures in the sieve tray, permitting the tray to function as would a standard sieve tray. However, when gas velocities increase, the valves respond thereto, and disengage themselves from the surface of the tray, permitting gas to travel upwardly through the apertures underneath the valves. This permits the modified sieve tray to operate efliciently at higher gas velocities.

The introduction of valves into a sieve tray generates certain additional disadvantages. Due to the development of eddy currents, the valves tend to rotate causing wear with eventual dislodgment of the valve from its aperture. In addition, the valves tend to weep, a phenomenon whereby liquid flowing across the tray passes downwardly through the apertures underneath the valve, before the gas velocity increases to an extent necessary to keep the liquid on the upper surface of the tray.

It will be apparent from the foregoing discussion that there is a need for a valve tray of improved construction which overcomes certain disadvantages of valve trays known to the prior art. The present invention is addressed to satisfying this need.

In accordance with the present invention there is provided in gas and liquid contact apparatus, a tray operative to commingle a liquid flowing across the upper surface thereof with a gas flowing upwardly therethrough, a plurality of apertures in the tray, valve means operatively associated with each aperture, and having an upstream side facing in the direction of liquid flow, the valve means being movable under the influence of gas flow from a closed position wherein the valve means is in sealing engagement with the tray, to an open position wherein at least a portion of the valve means is disengaged from the tray, and structural means interconnecting the upstream side of one valve means with the upstream side of at least one other valve means.

The structural interconnect defined above, serves the function of preventing rotation of the valves, thereby increasing the useful life, while maintaining maximum eificiency of the tray. Additionally, the interconnect serves to add mass to the upstream side of the valve, thereby causing that portion of the valve to lag in its response to increasing gas velocities. In this manner the weeping phenomenon is held to a minimum.

In accordance with another aspect of the invention the structural interconnect is configured to react downwardly, i.e., toward the tray in response to the force exerted by liquid flowing across the tray. This serves to further minimize the weeping phenomenon as a function of increased liquid velocities, and also to increase the amount of turbulence in the liquid phase, thereby improving the mass transfer efliciency of the tray.

In accordance with a further aspect of the invention the structural interconnect is provided with a plurality of openings along its length, and positioned to offer reduced resistance to the passage of low volume liquid flow. At higher volume liquid flow, these openings act as throttles, thus creating turbulence and utilizing the force of liquid fiow to keep the upstream side of the valve in contact with the tray, thereby minimizing the weeping phenomenon.

It is therefore an object of the present invention to provide a valve tray of improved construction.

A further object of the invention is to provide a valve tray which overcomes certain disadvantages of the prior art.

Another object of the invention is to provide a valve tray having valves which resist rotation, and which minimize the weeping phenomenon described above,

Yet another object of the invention is to provide a valve tray in which portions of adjacent valves are interconnected.

These and other objects and advantages will become apparent from the following detailed description of a preferred embodiment of the invention when read in connection with the accompanying" drawings, in which;

FIGURE 1 is a fragmentary schematic plan view of a preferred embodiment of valve tray;

FIGURE 2 is a schematic section view taken generally along line 2-2 of FIGURE 1;

FIGURE 3 is a schematic section view taken generally along line 33 of FIGURE 1;

FIGURE 4 is a fragmentary schematic plan view of a modification of the present invention;

FIGURE 5 is a schematic section view taken generally along line 5-5 of FIGURE 4;

FIGURE 6 is a fragmentary schematic plan view'of a second modification of the present invention; and,

FIGURE 7 is a schematic section view taken generally along line 7-7 of FIGURE 6.

Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the invention only, and not for the purpose of limiting the same, FIGURE 1 shows a fragmentary portion of a mass transfer tray 10, provided with perforations 12, giving the tray the character of a sieve tray.

Tray 10 is also provided with a plurality of apertures 14, each adapted to accommodate valve means, which in the embodiment illustrated takes the form of a generally circular valves 16, each having a slightly larger diameter than that of the aperture 14.

As best seen in FIGURE 2, the valve means is further provided with a plurality of depending stop flanges 18, adapted to limit the upward movement of valves 16. When the velocity of gas rising upwardly through tray 10 is low, valves 16 will assume the position shown in full line FIGURE 2. As the velocity of gas increases, the valves will rise to the extent permitted by depending stop flanges 18, and assume the position shown in phantom lines FIG- URE 2.

Valves 16 may be imperforate, but in the embodiment illustrated, are provided with perforations 20. When so provided with perforations, the valves will remain seated on tray 10 at somewhat higher gas velocity than would be the case where the valves are imperforate.

Depending stop flanges 18 may be formed from separate elements suitably attached to the underside of a valve 16, as by rivets or Welding, but in the embodiment illustrated, the flanges are stamped from the body of the valve, leaving slots 22.

The direction of liquid flow across the face of tray 10 is shown by arrows 24, and for purposes of this discussion the portion of valve 16 facing in the direction of liquid flow is deemed to be the upstream side of the valve.

The valve tray of the present invention is further provided with structural means interconnecting the upstream side of one valve means with the upstream side of at least one other valve means. In the embodiment illustrated in FIGURE 1, the structural means takes the form of bar 26, which may be fastened to valves 16, by any suitable means such as welding or rivets. However, in the embodiment illustrated, bar 26 is connected to valve 16 through slots 22. As best seen in FIGURE 3, the ends of bar 26 are bent downwardly and then bifurcated, to provide tabs 28. The tabs are then bent to either side of slot 22 to secure the bar to the valve.

As described above, the structural interconnect serves two functions. First, it serves to prevent a rotation of the valve in use, thereby increasing the life of the valve. Second, it serves to add mass to the upstream side of the valve, causing this side of the valve to lag behind the downstream side of the valve in becoming disengaged from tray 10, when the gas velocity increases, thereby minimizing the weeping phenomenon.

FIGURES 4 and show a modification of the present invention in which tray 30 is provided with a plurality of valves 32 each having depending stop flanges 34, and an interconnect in the form of a bar 36 formed integrally with valve 32.

With liquid flow in the direction shown by arrows 38, it will be noted that bar 36 is configured to react downwardly toward tray 30, in response to the force exerted by the liquid flowing across the tray. This arrangement improves the lagging characteristics of the leading edge of valve 32, and desirably, induces a degree of turbulence in the liquid flowing across the tray, somewhat improving the mass transfer efiiciency thereof.

FIGURES 6 and 7 show a second modification of the invention wherein tray 40 is provided with a plurality of valves 42 each having depending stop flanges 44. The structural interconnect between the valves comprises bar 46 mounted on rod 48 the ends of which are inserted in straps 50 formed integrally from valves 42. Bar 46 is provided with a series of openings 52 mounted along 4 its length near the bottom edge thereof. Liquid flows in the direction shown by arrow 54. At low flow rates openings 52 offer little resistance to the passage of liquid across the plate. However, at higher flow rates, openings 52 act as throttles, forcing the liquid over the top of bar 46 improving the lag characteristics of the leading edge of valve 42, and at the same time increasing liquid turbulence, whereby the mass transfer efficiency of the arrangement is improved.

The present invention has been described in conjunction with certain structural embodiments; however, it is to be appreciated that various structural changes may be made in the illustrated embodiments without departing from the intended scope and spirit of the present invention as defined in the appended claims.

Having thus described my invention, I claim:

1. In gas and liquid contact apparatus, a tray opera tive to commingle a liquidflowing across the upper surface thereof with a gas flowing upwardly therethrough; a plurality of apertures in said tray; valve means operatively associated with each aperture, and having an upstream side facing in the direction of liquid flow, said valve means being movable under the influence of gas flow, from a closed position wherein said valve means is in sealing engagement with said tray, to an open position wherein at least a portion of said valve means is disengaged from said tray; and structural means interconnecting the upstream side of one valve means with the upstream side of at least one other valve means, said structural means being an elongated strip having bifurcated tabs at both ends, and each of said valve means being provided with a slot adapted to receive a bifurcated tab.

2. In gas and liquid contact apparatus, a tray operative to commingle a liquid flowing across the upper surface thereof with a gas flowing upwardly therethrough; a plurality of apertures in said tray; valve means operatively associated with each aperture, and having an upstream side facing in the direction of liquid flow, said valve means being movable under the influence of gas flow, from a closed position wherein said valve means is in sealing engagement with said tray, to an open position wherein at least a portion of said valve means is disengaged from said tray; and structural means interconnecting the upstream side of one valve means with the upstream side of at least one other valve means, said structural means being configured to react downwardly, toward said tray, in response to the force exerted by liquid flowing across said tray, and being further provided with a plurality of openings along its length, positioned to offer reduced resistance to the passage of low volume liquid flow.

References Cited UNITED STATES PATENTS 2,627,397 2/ 1953 Hendrix. 3,245,669 4/1966 Huggins et a1. 3,287,004 11/ 1966 Nutter. 3,325,155 6/1967 Bahout.

HARRY B. THORNTON, Primary Examiner S. H. MARKOWITZ, Assistant Examiner US. Cl. X.'R. 261114